The invention relates to a viscous material metering system and method, in particular for supplying an organosiloxane (silicone) gum or other viscous material to a continuous compounding system.
In a compounding system, a material is fed to a processing line where feed is mixed and additives are injected in proportions to produce a customized product. The system requires precise and reliable dosing and feed operations to achieve uniform products with narrow tolerance properties. Accurately metering the material in a feed step can be critical to proper system operation.
However, it is difficult to separate an accurate quantity of a viscous material to feed a system from a bulk of the material. Accurate separation is difficult because of slow response of the viscous material to change in feed rate and because of the difficulty in separating a metered size or weight of the viscous material from a bulk of the material. The material may be resistant to pouring or if it can be poured, pour rate is extremely slow. A viscous material may exhibit high levels of adhesion or tendency to stick to other materials and/or cohesion or a tendency to remain stuck to itself and therefore resistant to separation. The viscous material may be shear thickening, exhibiting increasing viscosity as shear on the material is increased. It is difficult to feed accurate quantities of such materials so that an amount in a process can be controlled.
In some viscous material processes, a cutting tool such as a knife, blade or scissors is used to cut or dice portions of the material from a bulk or other quantity supply. For example, a feed portion of viscous material can be cut from a large bulk mass, from a pulled relatively thin cross-sectional string or from a generally cylindrical-shape of the viscous material by such tools. However, a relatively large force may be required and time and machinery may be required to move a blade or the like through a viscous material. Another disadvantage to moving a blade or the like through the material is the adherence of the material to the blade, especially if the material is sticky (highly adhering). The cutting tool may require frequent cleaning to remove accumulation of stuck material. Also, as the material sticks to the cutting tool, the force and work required to move a cutting tool through the material further increases.
Accordingly, there is a need to facilitate separating difficult-handling viscous material. Also, there is a need to accurately cut defined quantities of such material from a bulk quantity, regardless of the form of the bulk quantity and there is a need to accurately charge a viscous material to a processing system.